Cowi is to serve as consultant for the Japanese contractor IHI on a Turkish suspension bridge that will have the world’s fourth-longest main span.

The newly signed contract will see Cowi carrying out the detailed design of the Izmit Bay Bridge in cooperation with IHI. The bridge will be part of an extended highway system linking Izmir and Istanbul.

“The bridge over Izmit Bay is an extremely complex project with a free span of 1,550m between its pylons and a total length of about 3km," said Henrik Andersen, vice president of major bridges at Cowi.

"We have experience from a number of similar international projects, however. We’re currently consultants on the bridge over the Messina Strait in Italy which with a free span of over three kilometres will be the world’s longest upon completion,” he added.

Izmit Bay Bridge will be built in one of most seismically active areas in the world, which places additional demands on the bridge’s design. “The risk of an earthquake places unique demands on our services. Fortunately, we can draw on our earthquake specialists from our daughter company in California,” said project director Kent Fuglsang, who will head the nearly 80 Cowi engineers involved in the Izmit Bay Bridge design.

The overall price for the bridge will be about €800m (£699m). Construction is expected to start in the beginning of 2012 and will be completed in 2015. Cowi will provide consultancy services during the entire period. The Danish firm Dissing+Weitling is the architect of the bridge.